1. Field of the Invention
The present invention relates to a projection type image display apparatus provided with a photographing section capable of photographing a projected image projected on a screen through a projector lens to adjust the focus of the projected image by using the photographing section.
2. Description of Related Art
Conventionally, there is known a projection type projector which modulates a light emitted from a light source by an image projecting device, such as the DMD or the like, and which projects the modulated light onto a screen through an optical lens (projector lens) to display an image and the like. Moreover, in the projection type projector, because it is troublesome for a user to manually adjust the focus of a projected image, the so-called autofocus function for automatically adjusting the focus of a projected image is known.
In order to realize the autofocus function, a projection type projector equipped with a photographing section (for example, an image sensor of the CCD camera or the like) capable of photographing a projected image projected on a screen through a projector lens besides a projection section including a projector lens is proposed. For example, as shown in FIG. 6, there is a projection type projector that takes in a mark image TM projected on a screen through a projector lens L1 through a photographing lens L2, and that displaces the position of the projector lens L1 on the basis of the photographed image to automatically adjust the focus of the projected image (mark image).
Moreover, the following technique is disclosed as related art pertaining to the present invention.
For example, JP2006-098789A discloses a projection apparatus that simplifies troublesome setting operations at any projection position to easily project an image having an appropriate size and a shape. Particularly, the projection apparatus comprises a projection section to perform a projection display according to an input image signal, a photographing section to carry out the photographing in the projection direction of the projection section, an extraction section to extract the positions of a plurality of point marks indicating a projection range in the image obtained by the photographing section and a projection control section to variably set the projection range in the projection section in correspondence with the positions of the point marks obtained by the extraction section.
Moreover, for example, JP2005-241713A discloses a manufacturing method of an optical apparatus capable of accurately knowing a basic position of a light flux detection apparatus (for example, the CCD camera or the like) and a projector equipped with an optical apparatus manufactured by the manufacturing method. The optical apparatus enables to determine the accurate location of the basic position of the CCD camera as the light flux detection apparatus.
Moreover, for example, JP2003-015218A discloses a projection type display apparatus that simplifies the position adjustment and the like between an image projection section and a photographing section and that does not cause any parallax between a projected image and a photographed image. Particularly, the projection type display apparatus is equipped with the image projection section and the photographing section to photograph a projection surface and a subject situated on the projection surface, and allows a projection light to be output from the image projection section and a reflected light to enter the projection section from the projection surface or the subject through the same opening portion by a spectral section.
In the techniques disclosed in JP2006-098789A, JP2005-241713A, and JP2003-015218A, the projector lens constituting the projection section and the photographing lens constituting the photographing section are separately provided, and the respective lenses are connected to separate drive sections. That is, the respective lens positions can be adjusted independently, and the focus of the projected image and the photographed image can be adjusted separately. As described above, when the projector lens and the photographing lens are driven by respectively different drive sections, the accuracy of the drive sections is not necessarily the same. Therefore, even when the position of the projector lens is adjusted on the basis of the photographing result by the photographing section, for example, even when the moving amount of the projector lens is adjusted in conjunction with the moving amount of the photographing lens, errors are produced in no small quantities.
Moreover, there is also a case where the focus of a photographed image can be regarded as being adjusted by using a photographing lens having a large depth of field even when the position of the photographing lens is not particularly adjusted by the drive section. In this case, it is considered that the necessity of independently providing a drive section for the position adjustment of the photographing lens is low.